docs: def realtime_stream(self, channel=1, typeno=0, path_file=None):
          """
          If the stream is redirect to a file, use mplayer tool to
          visualize the video record
  
          camera.realtime_stream(path_file="/home/user/Desktop/myvideo)
          $ mplayer /home/user/Desktop/myvideo
          """
          ret = self.command(
              'realmonitor.cgi?action=getStream&channel={0}&subtype={1}'.format(
                  channel, typeno)
          )
  
          if path_file:
              with open(path_file, 'wb') as out_file:
                  shutil.copyfileobj(ret.raw, out_file)
  
          return ret.raw